Please use this identifier to cite or link to this item:
Other Titles: 150376-330425-1-PB.pdf
Authors: A. Kasimov, K. Korytchenko, D. Dubinin, A. Lisnyak, I. Khmyrov E. Slepuzhnikov, I. Khmyrov
Keywords: холодний пуск, дизельний двигун, чисельне дослiдження, процес стиснення, полегшення пуску
Issue Date: 2018
Citation: Eastern European Journal of Enterprise Technologies/Східно-Європейський журнал передових технологій/Восточно-Европейский журнал передовых технологий
Series/Report no.: ;Сторінки 49-53
Abstract: In the diesel engines fuel ignition occurs by compressing the air charge in the engine’s cylinder. During compression, there is an increase in the pressure and temperature of the charge. The reliable ignition and rapid fuel combustion, which is injected into the engine’s cylinder, temperature of the air charge must exceed 450‒500 °C [1, 2]. When starting an engine at low ambient temperatures, temperature of the air charge may not reach the specified limit, which leads to a failure in the engine start or to an increase in the emission of harmful substances. A de crease in the charge temperature is due to the following processes. When the air charge is compressed, it is cooled by the cold walls of the engine’s cylinder. There occurs an increase in the leakage of part of the air charge due to the lowered seal in the pair piston-barrel due to the insufficient thermal expansion of cold parts of the engine’s cylinder-piston group. In engines with a turbocharger, the starting rotations are accompanied by a decrease in the degree of compressor compression, which also reduces the temperature of the intake air. In these cases, auxiliary means are used to facilitate the start of internal combustion engines.  A. Kasimov, K. Korytchenko, D. Dubinin, A. Lisnyak, E. Slepuzhnikov, I. Khmyrov, 2018 NUMERICAL STUDY OF THE PROCESS OF COMPRESSING A TURBULIZED TWOTEMPERATURE AIR CHARGE IN THE DIESEL ENGINE A. Kasimov Department of General Military Disciplines Military Institute of Tank Forces National Technical University "Kharkiv Polytechnic Institute" Poltavskiy shlyakh str., 192, Kharkiv, Ukraine, 61098 Е-mail: K. Korytchenko Doctor of Technical Sciences, Senior Researcher Department of Electrical Engineering National Technical University "Kharkiv Polytechnic Institute" Kyrpychova str., 2, Kharkiv, Ukraine, 61002 E-mail: D. Dubinin PhD* Е-mail: A. Lisnyak PhD, Associate Professor* E-mail: E. Slepuzhnikov PhD Department of special chemistry and chemical technology** Е-mail: I. Khmyrov PhD Department of prevention activities and monitoring** Е-mail: khmyrov *Department of fire tactics and rescue operations** **National University of Civil Defence of Ukraine Chernyshevska str., 94, Kharkiv, Ukraine, 61023 Дослiджувалася проблема пiдвищення енергоефективностi систем полегшення пуску дизельних двигунiв за рахунок пiдiгрiвання повiтряного заряду. В основу пiдвищення енергоефективностi закладено пiдiгрiвання лише частини заряду. У результатi в цилiндрi двигуна утворюється повiтряний заряд, що складається з двох шарiв повiтря з рiзною температурою. Для обґрунтування нового методу полегшення холодного пуску багатолiтрового дизельного двигуна проведено чисельне дослiдження стиснення рiзнотемпературного повiтряного заряду в двигунi. Чисельно дослiджувалася змiна температурного поля заряду пiд час стиснення з урахуванням вихрових потокiв, що виникають при формуваннi заряду в цилiндрi двигуна на прикладi двигуна типу 6ТД. З аналiзу температурного поля заряду виявлено наявнiсть умов для надiйного самозаймання палива у зарядi пiд час його стиснення. Для формування двох шарiв повiтря, що мають рiзну температуру, за умов моделювання задавалося спочатку нагнiтання холодного повiтря в цилiндр двигуна при температурi 253 K. Далi здiйснювалось нагнiтання пiдiгрiтого повiтря при температурi 773 K. Об'ємна доля пiдiгрiтого повiтря в зарядi склала 10 %. За результатами моделювання виявлено, що при стисненнi зберiгається наявнiсть шарiв заряду з рiзними температурами. Пiдтверджено досягнення температури самозаймання палива в попередньо пiдiгрiтому шарi повiтря при температурi впускного повiтря – 20 °С. Отриманi результати можуть бути використанi для обґрунтування вимог до енергоефективних систем полегшення холодного пуску дизельних двигунiв Ключовi слова: холодний пуск, дизельний двигун, чисельне дослiдження, процес стиснення, полегшення пуску UDC 621.436 DOI: 10.15587/1729-4061.2018.150376 Eastern-European Journal of Enterprise Technologies ISSN 1729-3774 6/5 ( 96 ) 2018 50 As regards powerful engines, there are commonly applied auxiliary means for a cold start, which enable the heating of an engine in general or the heating of air that enters the engine’s cylinder [3]. Warming up an engine in general is energetically costly and requires a lot of time [4]. Heating the intake air is more energy efficient compared to energy consumption when warming up an engine. However, this method for start facilitation has certain disadvantages. In particular, the application of torch air heaters leads to a significant reduction in the concentration of oxygen in the intake air, which causes a failure to start or a prolonged engine start. Electric air heaters require excessive high power, which leads to the additional load on a rechargeable battery with a corresponding decrease in the probability of starting the engine [5, 6]. In order to increase energy efficiency of the start, it was proposed to heat only a part of the intake air to create a two-temperature air charge in the engine’s cylinder [1]. Thus, it is a relevant task to improve energy efficiency of the systems that would facilitate the start of diesel engines based on heating a part of the air charge.
Description: A task on improving energy efficiency of the system that facilitates the start based on the heating elements was addresses in paper [7]. It was proposed to connect an electric heating element to the power source with variable voltage, which changes over time in line with a specialized algorithm. The application of such a technique to facilitate the start made it possible to ensure a reliable start of the engine at an inlet air temperature of −25.5 °С to −16 °С, to reduce the time required to heat the system before the start to 10 seconds, to limit a voltage drop at rechargeable batteries to 15 %. However, this system provides the heating of the entire volume of air that enters an engine, which is a constraint for the further improvement of the start energy efficiency. The authors of papers [8, 9], based on the results of experimental studies, revealed another issue related to a cold start of the diesel engine when biodiesel fuel or liquefied gas are used. They identified the reduced indicator work in such engines at a low inlet air temperature. This testifies to the need to increase the temperature of the intake air, which requires the employment of energy-efficient systems that facilitate the start. Paper [10] investigated the development of a flame in the engine’s cylinder at an inlet air temperature of −29 °C. The displacement of the flame front was determined based on its optical radiation. The authors found that the spontaneous combustion of fuel occurred in a zone of the elevated temperature near a spark plug. This allowed them to argue on that the presence of a local high-temperature zone in an air charge would be enough to ensure the conditions for the self-ignition of fuel. A variant to solve the problem on cold starting the engines equipped with spark plugs, investigated in [11], implied the injection of a pilot portion of fuel. It was found that combustion of the pilot portion of fuel creates a high-temperature zone in the charge. That is why, during subsequent injection of the main portion of fuel, there are conditions in the charge for its intense combustion. Thus, the formation of a high-temperature layer in the air charge enables a reliable start of the diesel engine. The research, reported in paper [12], shows a more acute problem related to cold-starting the diesel engines with a turbocharger. This is due to the reduced compression ratio in such engines. That is why there is an increase in the number of diesel power units that are equipped with systems to facilitate their cold start. Study [13] addressed the effect of the cold state of an engine on the toxicity of combustion products. It was established that an increase in the air charge temperature inside an unwarmed engine results in the more complete fuel combustion and reduces the emissions of harmful substances. Papers [1, 14] proposed a new method for facilitating the start, whose energy efficiency is ensured through heating, beyond the engine’s cylinder, only a part of the inlet air. As a result, a two-layer air charge with different temperatures forms in the cylinder. Based on the results of numerical studies into the process of compression of an ideal two-temperature charge, the presence of conditions for the reliable fuel self-ignition was established [14]. Along with this, paper [14] failed to consider the effect of turbulent eddies of air that emerge in the engine’s cylinder at the time when it is filled with an air charge. The above allows us to argue about the expediency of conducting a study into the process of compression of the turbulized two-temperature air charge, in order to elucidate the conditions for reliable fuel self-ignition in the diesel engine.
Appears in Collections:Кафедра наглядово-профілактичної діяльності

Files in This Item:
File Description SizeFormat 
150376-330425-1-PB.pdf543,1 kBAdobe PDFView/Open

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.